Figure 4.

Endonucleolytic cleavage of U1 snRNA by TaqN. A variant of U1 RNA (29) labeled in its 5′ end cap with ³²P was incubated for 15 min at 55°C with 50 ng of TaqN in 10 μl of 10 mM Mes, pH 6/100 mM NaCl/50 mg/ml tRNA buffer/1 mM MnCl₂ (lanes 1 and 3). Size markers were generated from the RNA by digestion with 0.1 unit of RNase T1 in 10 mM Tris⋅HCl, pH 8/1 mM EDTA buffer at 37°C for 10 min (T1, lane 4) or 25 mM Tris⋅base, pH 9.4/9.5 for 3 min (OH⁻, lane 5).